Physical refining of rice bran oil in relation to degumming and dewaxing

Abstract

Physical refining of rice bran oil (RBO) with acidity between 4.0 and 12.4% has been investigated in relation to degumming and dewaxing pretreatments. It appears that physical refining after combined low-temperature (10°C) degumming-dewaxing produces good-quality RBO with respect to color, free fatty acid, oryzanol, and tocopherol content. JAOCS 75, 1683JAOCS 75, -1686JAOCS 75, (1998. KEY WORDS:Degumming, dewaxing, physical refining, rice bran oil.Rice bran oil (RBO) of edible grade contains 2.0-20.0% free fatty acids (FFA), depending on the quality of bran. It is difficult to refine RBO because of its high FFA, unsaponifiable matter (UM), and color.Among the various approaches for refining high-as well as low-FFA RBO, the most widely used steps are degumming, dewaxing, neutralization of FFA, bleaching, and deodorization. However, the major problems of chemical refining are production of large quantities of soap stock, high refining losses, and environmental pollution (1).Bhattacharyya et al.(2) proposed a process for obtaining edible-quality oil from high-FFA RBO by a combination of miscella dewaxing and miscella refining. Deacidification of high-FFA RBO (15-30%) by re-esterification with glycerol and alkali neutralization also has been proposed (3,4). This combined process, followed by bleaching and deodorization, yields good-quality oil.Biorefining, i.e., removal of FFA by esterification with added glycerol and specific lipases, is a newer approach. Bhattacharyya et al. (5) have successfully developed a process to bring down the FFA from 30 to 3.6% for RBO, and subsequent alkali refining, bleaching, and deodorization produced excellent-quality RBO. The main barrier of this process is the cost of the enzyme.There has been growing interest in physical refining of RBO. The process is attractive because of its simplicity, lack of environmental impact, low oil losses, and good-quality product (6). Physical refining removes the FFA, thereby eliminating soap stock and reducing neutral oil losses to minimal levels. Prabhakar et al. (7) have reported that the higher refining loss of RBO and darkening of color is due to the existence of wax, oryzanol, and phosphatides. Practical experience has shown that acceptable results may be obtained during physical refining if good-quality raw material is used. Incomplete removal of undesirable components during pretreatments also affects the quality of the final product.The removal of lipid and nonlipid components during degumming, dewaxing, and bleaching is therefore of prime importance. This investigation has focused on the removal of gummy materials and waxes under various conditions prior to physical refining, so that the quality of RBO as a final product is not impaired. MATERIALS AND METHODSCrude RBO of varying acidity were supplied by local oil mills.FFA, peroxide value (PV) and UM in crude and refined oils were determined according to standard AOCS methods (8). Color of the crude and refined oils was determined with a Lovibond Tintometer (8).Total gum and wax content w...

Deacidification of High-acid Olive Oil

“…These approaches, however, lead to high refining loss when applied to high-FFA oils. Therefore, several authors have proposed physical refining for high-FFA oils [5][6][7][8]. This process removes FFA along with odoriferous compounds by purging saturated steam through the oil at *Corresponding author: Mohamed Fawzy Ramadan, Biochemistry Department, Faculty of Agriculture, Zagazig University, 44519 Zagazig, Egypt, Tel: 002 012 9782424 or 002 055 2320282; Fax: 002 055 2287567 or 002 055 2345452; E-mail: hassanienmohamed@yahoo.com a high temperature under high vacuum.…”

Rice bran oil, the Future Edible Oil of India: A mini Review

“…Studies have proved that gamma oryzanol is four times effective than tocopherols in inhibiting cellular oxidation [10]. Rice bran oil serves as an important functional food and possesses following health benefits:…”

Simple Techniques to Increase the Production Yield and Enhance the Quality of Organic Rice Bran Oils

“…Simple refi ning processes were selected from a number of techniques provided in the literatures [10][11][12][13] . CRBO extracted at different conditions described above was subject to simple refi ning process involving mostly physical refi ning and without hazardous chemicals.…”

“…Peroxide values PV and FFA were determined by standard AOAC methods 15 . Total gum and wax content was estimated as the percentage acetone-insoluble matter in the oil following the method described by De and Bhattacharyya 10 . Oryzanol content was determined by measuring the optical density of the oil in hexane solution at 315 nm and using the specifi c extinction coeffi cient for oryzanol 16 .…”